There seems to be an issue with Wards against Fire in canon spells.
While we have guidelines for warding against Fire (level 20 against +10, level 25 against +15, etc.), the two canon spells we have, Ward against Heat and Flame and Ward Against Immolation, instead use the base 4 guideline to prevent a fire from touching the person, with added magnitudes to deflect stronger flames. And they also give a bonus Soak against fires, so unlike the Ward guidelines, they are effective against fire even stronger than they can protect.
That seems to be at odds with the guidelines.
I understand the level 20 guideline, stripped of the Touch and Ring/Circle, would be level 5 against +10, but it's still not giving a bonus to Soak against stronger fires. Wards generally either work or they fail.